Treatment of sulphite liquor



Feb. 5, 1957 A. E. RElNl-:RT

TREATMENT oF SULPHTTE LIQuoR Filed Jan. 9, 1952 INVENTOR. BY Q .(5.0 W124/nml? ETEA Il EMM/05M United States Patent Tice t V2,780,281 TREATMENT oF fsULPHITE LIQ'UoR Armin Erkeinertg'shawanb, Wis., assigner of one-half to HerbertH. Clark, Oshkosh, Wis.

Application January 9, 1952, snat No; '265,700 1 Claim. (Cristi-aas) The present -invention Irelates generally `to improveinents 'in'the art of V'treating 'solid bearing li'quids in forder 'to removeexcess liquid-fromfthe solutionsyandrelates more specically 'to an 'improved method and/ or Jsystem for concentrating -sulphite liquorproduc'ed by 'the sul- -phite process'in paper pulpl mills.

The primary object of =my invention is "to `provide 'an economical and eicient method'of lconcentrating s'ulphite liquor with the faid 'of "an automatically l'functioning sysi tenrcomposed*ofisirnple apparatus.

iThe fconciitration" 'and 'disposal "fof: `'spent sulpliite iliq- V'uorfrom 'lp'aperipulp "niills "utilizing the sulphite process ofmanufacturing paper-has heretofore been ia major problem, and while many diierent methods anditype's of f "Aritheni important A 'object ofthe invention is to pro- Jv'ide ia-r'riewth'd of commercially concentrating-sulpliite liqiior, by -riefrigeration, siibliiiiation; and vpressure` applicationin afcontinuons Meffective manner.

, Afrth-erd-impor'tant object ofmy invention "isitopro- 'systeinfutilizing relatively `standard equipmentV assembled `-so as-to constantly treat large `volnrnesjof the liquidrin lflland effective mannen,

` Still another important object of`this invention is to provide a closedfciriitisystefri'iforremoving excess liquid 2,780,281 Patented Feb. V5, a1-95,7

the improved method, and -of-the`construction and functioning vof a commercial lsystem involving this method, `may be had by referring'fto the drawingaccompanying and forming a part of this specification wherein the'vari- -ous parts are identified both by -name and by suitable reference characters.

The single figure -of the'drawing is a diagram depicting a typical commercial'embodiment Yof a *system for continuously 'exploitingthe improvedfmethod of concen- :trating sulphiteliquor rdelivered thereto in heated condition from the pap'eror'pulp mill.

While only one typical assemblageof apparatus adapted to deliver the nal product in liquid but highlyV concentrated condition,A has been shown and described by way of illustration, itis not Athe vintention to. unnecessarily restrict the use of `the particular-apparatus illustrated` by virtue of this limitedshowing; and it is also contemplated that speciiic descriptive terms employed herein be given `the lbroadest possible interpretation consistent with the disclosure.

Referring to the drawing, the typical systemdiagram illustrated, Acomprises -in general, `a rubber lined tank 2 'havingl a fresh -and `hot sulphite liquor inlet 3 Vnear 'its 'medialportiona`nd being provided at its upper end with *a vapor outlet 4 and Vitslower end with an initially cooled Y liquor `discharge conduit-5; a barometric or similar convide andinprovdspentvpaper mill-'liquor concentrati-ng ,55`

vdenser 6-conimun-icating 'with jthe supply tank outlet 4 and having a coolingfwat'erinlet pipe 7 and a Vvacuum 4,producer fasso'ciated `with itsiupper end while its lower portion isz-providedwith the usual tailpipe 9; a centrifugal pump liffor'receivingV liquid from the tank disehargefconduit` Sand fo'rzdelivering this initially cooled liquid ith-rough another 'conduit :1l into arhighfpressure hydraulic pump lh'aving a=discharge line 13; a heat exchanger `orV refrigerator 1114 cooperating with the high pressurelinelEi-to materially 'reduce `the temperature of the liquid 'flowing therethrough; -a housing 15 forming lan enlarged closed-chamber 16, and a spray nozzle 17 "at thedeliveiry endeof'the -high pressure line 13 within the chamberfl'oadjacent `toene-end wall of the housing 15'; an induced draft'fan' adjacent to the opposite end wall of the housing 15 for removing vapors separated by sublimation 4within warmerportions of the chamber 16";a11d for urging-:these vapors through a second heat ex- 'changerf19 adapted to'admit cool fresh air to thefchamyber 16 'throughvan air duct "26 -and 'the refrigerator 14; a series of hoppers 21 at the bottom of the chamber 16 each havingarpain'of :cooper-ating press rolls 22 therebelow; a1concentratedfliquorreceiving tank `23; located Abelowithefpressrrolls 22`and having therein an endless -perforated conveyor 24C forf separating vthe solid ice de- ?liveiedrbyftherollsfrom the treated liquor; a trough 25 'fat 'the delivery 'en'd of'theV conveyor 24 havingsuitable ycontrols iforl liquiddelive'red therefrom; and awcentrifugal pump 26forwithdrawingicecold-water from the trough H25'iand` foretran'sporting '.this'liquid through the pipe 7.

The rubberlinedftanliilispreferably formed of steel or Iother-'suitablemetal, "and the 'condenser 6 may be of the"barometriclor any tother suitable type adapted to create a high degree of-vacuumwithin the tank Zand to `condenseland constantly'remove the vapors rising from the *hot snlphite 'liquoradniitted'through the inlet 3. VBy virtue of the fact that the condenser 6 is operable by ice cold water controllably admitted from the trough 25 by the pump 26 through the supply pipe '7, and that the vapors Aare rapidly removed from the tank 2 without applying heat and thereby eliminating scaling, the temperature of the fresh liquor admitted at the inlet 3 is promptly reduced from approximately 220 F. to somewhat below atmospheric temperature. l

The centrifugal pump 10 -is operable to constantly transfer the initially cooled sulphite liquor from the conduit 5 through the conduit 11 into the high pressure hydraulic pump 12 which should preferably be of a type adapted to deliver the liquor at a pressure in excess of two thousand pounds per square inch to the refrigerator 14 through the spray pipe 13. The refrigerator may be operated by ammonia or any other type of refrigerant admitted in liquid form through a lower inlet 28 and discharged in gaseous condition through an upper outlet 27, and this refrigerator 14 should be adapted to somewhat lower the temperature of the liquid flowing through the line 13 to the spray nozzle 17, and to also lower the temperature of the fresh pre-cooled air admitted through the lduct 20 considerably below water freezing temperature and preferably to about 20 F.

The refrigerated fresh air is delivered from the heat exchanger 14 into the chamber 16 around the spray nozzle 17 and the housing 15 should preferably be formed of wood or other relatively good insulation so as to prevent excessive heating of the upper portion of the chamber 16 wherein the nozzle 17 converts the sulphite liquor into snow. The hoppers 21 at the bottom of the housing 15 need not be so Well insulated so that somewhat warmer temperatures will exist therein and will remove considerable moisture from the snow by sublimation. This moisture is withdrawn from the chamber 16 by the exhaust fan 18 and is condensed in the heat exchanger 19 from which the liquid of condensation is discharged through a drain 30 while the gases escape through a stack 31. Fresh cool air may be admitted to the heat exchanger 19 through an inlet 32 and is delivered thereby through the duct 20 to the refrigerator 14.

The hoppers 21 are adapted to receive the snow delivered from the nozzle 17 and by the cold air from the refrigerator 14 as shown, and the press rolls 22 should be constantly operated to simultaneously compress the snow flakes into solid ice particles and to express the residual sulphite liquor from the ice. The perforated endless conveyor 24 should be located within the sulphite liquor collecting tank 23 with the upper conveyor run directly beneath the press rolls 22 and constantly advancing toward the trough 25, so that the concentrated sulphite liquor will Idrop into the tank 23 and may be withdrawn through the lower tank outlet 33 while the solid ice particles will be discharged over a chute 34 into the trough 25. The ice particles will contain only pure water but may have some solid ingredients of the sulphite liquor adhering to the surface Y thereof, and these may be washed olf into the tank 23 by fresh water delivered through a nozzle 35 before they reach the chute 34.

The trough should be kept supplied with an abundance of water the temperature of which will be constantly reduced to approximately 32 F. by the ice cubes or particles delivered thereto by the conveyor 24, and the 'centrifugal pump 26 should be continuously operated and controllably fed from the trough 25 so as to deliver and abundant supply of ice cold water through the pipe t 7 to the barometric condenser 6. The refrigerator 14 and the several pumps thus function to keep the condenser 6 operating at maximum eciency and to reduce the degree of refrigeration required to a minimum, by maintaining a constant circulation of cold liquid through the initial elements of the system.

The automatic functioning of the entire system in order to effect continuous exploitation of the improved method of concentrating the sulphite liquor, should be clearly apparent from the foregoing description of the construction and operation of the apparatus; and while the various pumps, heat exchangers and lother elements are standard and readily available equipment they must necessarily cooperate in a particular manner in `order to obtain the desired results. While the concentrated liquor is still in liquid form with its percentage of solid constituents considerably increased upon a single pass through the system, the liquid content may be substantially eliminated by subjecting the product of the rst concentration to further treatmentin one or more successive similar systems or special evaporators.

From the foregoing detailed description it will be obvious that my improved method is not only highly eflicient and adapted for commercial use in large or small paper and pulp installations, but it may also be exploited with relatively standard and inexpensive equipment properly assembled and operated. The concentration of the sulphite liquor is accomplished in successive `stages not only by refrigeration and vacuum, but by sublimation in the chamber 16 and linal compression between the press rolls 22; and by utilizing the solid ice separated by these rolls to cool the liquid which operates the condenser 6, maximum economy of operation results.

It should be understood that it is not desired to limit this invention to the exact steps of the method or to the precise apparaus for exploiting the method, herein specilically described and shown, for various modifications within the scope of the appended claims may occur to persons skilled in the art.

I claim:

The method of continuously concentrating spent hot sulphite liquor delivered from paper mill digesters and which contains excess water, which method comprises, initially subjecting the hot liquor to a partial vacuum to remove some of the excess water in the form of vapor, thereafter subjecting the partially dehydrated liquor to high pressure and to low temperature and spraying the same through a restricted orifice into a confined space to convert the liquor into snow containing congealed water and concentrated sulphite liquid, mechanically separating the congealed water from the concentrated sulphite liquid, heat treating the congealed water to convert it into cold liquid water, and condensing the vapor initially removed from the hot liquor by subjecting said vapor in heat exchange relationship to cold liquid water obtained from said congealed water separated from the snow.

References Cited in the file of this patent UNITED STATES PATENTS 981,860 Jackson Ian. 17, 1911 1,273,208 Weil July 23, 1918 1,976,204 Voorhees Oct. 9, 1934 2,009,283 Warner July 23, 1935 2,312,474 Peebles Mar. 2, 1943 2,411,152, Folsom Nov. 19, 1946 2,471,035 Hurd May 24, 1949 2,533,125 Levinson et al. Dec. 5, 1950 2,542,041 Mason et al Feb. 20, 1951 2,556,250 Bauman June 12, 1951 2,595,852 Hopper May 6, 1952 Y FOREIGN PATENTS 243,982

Great Britain Dec. 10, 1925 ker..- i 

